The continuing accumulation of used tires is one of the worst solid waste problems facing industrialized countries. It is estimated that North America discards approximately one used tire per person per year. The incineration of tires is both costly and complex, while stockpiling used tires is the subject of growing concern. Moreover, the possibility of tire fires on these sites poses an ever-increasing threat to the environment. On the other hand, tires represent a source of energy and chemicals. By thermal decomposition, it is possible to recover useful products in an environmental friendly way.
The presence of terpenes in “Py-oil” or rubber pyrolysis oil has been known for decades. However, the concentration is low. Attempts to separate the terpenes via distillation have been counterproductive because the heat required for distillation results in decomposition of the most valuable terpenes, such as limonene. Simply reducing the pressure of the distillation results in very high costs from large columns and long processing residence times. Also, there is great difficulty in separating odiferous mercaptans, and complications from sulfur content, water content and solids.